1. Field of the Invention
The present invention relates to a communication apparatus and, more particularly, to a communication apparatus realized such that a telephone set and a data communication apparatus for performing data communication using a predetermined scheme are connected to predetermined communication lines.
2. Related Background Art
A typical communication system of the type described above is a system in which a plurality of telephone sets and non-speech communication apparatuses such as facsimile systems are connected to a plurality of telephone lines, as shown in FIG. 6.
Referring to FIG. 6, two telephone lines (station lines) 2a and 2b are connected to main equipment 2. The main equipment 2 performs switching of three Touch-Tone Keypad phones 4, 6, and 8 and a fax machine 10 through the two telephone lines 2a and 2b.
The illustrated telephone set is not a device which cannot be coupled to the telephone lines to perform communication by itself, and circuits for controlling communication such as an incoming call and an outgoing call, a speech path, and a power supplier are included in the main equipment 2. Outgoing and incoming call control of each telephone set is automatically performed by the main equipment 2.
The fax machine 10 is a device which can be connected to the telephone lines to perform communication with other fax machines by itself. When the fax machine 10 is connected to the telephone lines together with the speech system comprising the Touch-Tone Keypad phones 4, 6, and 8 and the main equipment 2, a selector (not shown) is used to manually set the telephone mode or fax mode. A signal line 10a for connecting the fax machine 10 and the main equipment 2 comprise a pair of lines for communication. Each of signal lines 4a, 6a, and 8a for connecting the Touch-Tone Keypad phones and the main equipment 2 comprises a pair of speech lines and a pair of control power supply lines.
In the conventional system described above, the fax machine can be simply connected to the main equipment for the telephone sets. When the fax machine is not used, functions are limited such that an outgoing call can be made using fax communication lines. In addition, the fax machine itself can be connected to the station lines, and the system has a double line control function together with the control operation of the main equipment 2. As a result, the conventional communication system cannot be regarded as an economical system.
A functional relationship between the telephone system and the fax machine is not present at all. It is impossible to control the fax machine from the Touch-Tone Keypad phone. When an operator performs communication using the fax machine, he or she must leave his or her desk and go to the installation place of the fax machine. In order to check reception of image data or completion of sending by the fax machine, although the operator does not actually send information, he or she must go to the installation location of the fax machine.
The above problem is common in all data communication apparatuses in addition to the fax machine connected to the communication lines.
When a communication apparatus such as a fax machine is connected together with a plurality of telephone sets, only one fax machine receives all pieces of information. Therefore, the destinations of these pieces of information cannot be determined, and one of the operators must recover all recorded sheets and distribute them to the proper destinations.
The above problem can be solved by preparing fax machines to all staff or fax machines integral with telephone sets. However, even if a large number of fax machines are connected to a single speech path, communication cannot be performed simultaneously, thus imposing excessive investment on users.
The above situation cannot be improved even if the apparatus connected together with the telephone set is not a fax machine but a data terminal. It should be noted that U.S. patent application Ser. No. 823,286 filed by the present applicant describes a system in which two telephone sets and one fax machine are connected to two telephone lines.